using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using System.Runtime.Serialization;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/64474856/c-sharp-using-newtonsoft-json-defaultcontractresolver-ivalueprovider-to-replace

​

  public class JsonTester

  {

    public void Test()

    {

      var d = new Outer();

​

      var json = JsonConvert.SerializeObject(d, new JsonSerializerSettings()

      {

        ContractResolver = new JsonContractResolver()

      });

    }

  }

​

  public interface IVariant

  {

    object Data { get; }

​

    string TypeName { get; set; }

  }

​

  public interface IVariantData

  {

  }

​

  [DataContract]

  public class Variant<TEnum, TData> : IVariant where TEnum : struct where TData : class, IVariantData, new()

  {

    [DataMember]

    public TData Data { get; }

​

    public string TypeName { get; set; }

​

    object IVariant.Data => Data;

​

    public Variant()

    {

      Data = new TData();

    }

  }

​

  [DataContract]

  public sealed class VariantHolder

  {

    [DataContract]

    public class Joystick

    {

      [DataMember]

      public string Test { get; set; } = "Test";

    }

​

    [DataContract]

    public class Button

  {

    [DataMember]

    public string Test2 { get; set; } = "Test2";

  }

​

    [DataContract]

    public sealed class AimΞVariant : Variant<AimΞVariant.VariantEnum, AimΞVariant.VariantData>

  {

    public AimΞVariant()

    {

      TypeName = "Button";

    }

    public enum VariantEnum : byte

    {

      Joystick,

      Button

    }

​

    [DataContract]

    public sealed class VariantData : IVariantData

    {

      [DataMember]

      Joystick _Joystick = new Joystick();

​

      [DataMember]

      Button _Button = new Button();

​

      public Button Button => _Button;

      public Joystick Joystick => _Joystick;

    }

  }

​

    [DataMember]

    AimΞVariant Aim = new AimΞVariant();

  }

​

  [DataContract]

  public sealed class Outer

  {

    [DataMember]

    VariantHolder Data = new VariantHolder();

  }

​

  public class JsonContractResolver : DefaultContractResolver

  {

    public JsonContractResolver()

    {

​

    }

​

    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

    {

      return base.CreateProperty(member, memberSerialization);

    }

​

    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)

  {

    var list = type.GetProperties().Where(x => x.GetCustomAttributes().Any(a => a.GetType() == typeof(DataMemberAttribute))).Select(p =>

    {

      var member = p.GetCustomAttribute<DataMemberAttribute>();

​

      return new JsonProperty()

      {

        PropertyName = p.Name,

        PropertyType = p.PropertyType,

        Readable = true,

        Writable = true,

        ValueProvider = CreateMemberValueProvider(p),

        DefaultValueHandling = DefaultValueHandling.Include

      };

    }).Concat(

    type.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public).Where(x => x.GetCustomAttributes().Any(a => a.GetType() == typeof(DataMemberAttribute))).Select(p =>

    {

      var member = p.GetCustomAttribute<DataMemberAttribute>();

      return new JsonProperty()

      {

        PropertyName = p.Name,

        PropertyType = p.FieldType,

        Readable = true,

        Writable = true,

        ValueProvider = CreateMemberValueProvider(p),

        DefaultValueHandling = DefaultValueHandling.Include

      };

    })).ToList();

​

    return list;

  }

​

    protected override IValueProvider CreateMemberValueProvider(MemberInfo member)

    {

      Type type = member.MemberType == MemberTypes.Property ? ((PropertyInfo)member).PropertyType : ((FieldInfo)member).FieldType;

​

      if (typeof(IVariant).IsAssignableFrom(type))

      {

        return new IVariantValueProvider(member, type);

      }

​

      return base.CreateMemberValueProvider(member);

    }

  }

​

  internal class IVariantValueProvider : IValueProvider

  {

    private MemberInfo member;

    private Type type;

​

    public IVariantValueProvider(MemberInfo member, Type type)

    {

      this.member = member;

      this.type = type;

    }

​

    public object GetValue(object target)

    {

      IVariant variant;

      switch (member)

      {

      case PropertyInfo p:

        variant = (IVariant)p.GetValue(target);

        break;

      case FieldInfo f:

        variant = (IVariant)f.GetValue(target);

        break;

      default:

        throw new InvalidCastException();

      }

​

      var dataType = variant.TypeName;

​

      var property = variant.Data.GetType().GetProperty(dataType);

​

      var value = property.GetValue(variant.Data);

​

      return value;

    }

​

    public void SetValue(object target, object value)

    {

      throw new NotImplementedException();

    }

  }

// Fixed - removed extra }

//}

​

    class TestClass

    {

        public static void Test()

        {

            new JsonTester().Test();

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​